<template>
   <div class="goods">
     <!--Vue1.0是使用 v-el 指令来绑定元素，格式为：短横线拼接命名；在Vue2.0中 被 ref 指令替代了，格式为：小驼峰命名-->
     <!--温馨提示：此处不可使用短横线命名的方式，如 此处写 foods-wrapper 是不行的-->
     <div class="menu-wrapper" ref="menuWrapper">
       <ul>
         <li v-for="(item, index) in goods" :key="index" class="menu-item" :class="{'current':currentIndex===index}" @click="selectMenu(index, $event)">
           <span class="text border-1px"><span v-show="item.type > 0" class="icon" :class="classMap[item.type]"></span>{{item.name}}</span>
         </li>
       </ul>
     </div>
     <div class="foods-wrapper" ref="foodsWrapper">
       <ul>
         <li v-for="(item, index) in goods" :key="index" class="food-list food-list-hook">
           <h1 class="title">{{item.name}}</h1>
           <ul>
             <li @click="queryDetail(food, $event)" v-for="(food, foodIndex) in item.foods" :key="foodIndex" class="food-item border-1px">
               <div class="icon">
                 <img width="57" height="57" :src="food.icon"/>
               </div>
               <div class="content">
                 <h2 class="name">{{food.name}}</h2>
                 <p class="desc">{{food.description}}</p>
                 <div class="extra">
                   <span class="count">月售{{food.sellCount}}份</span><span>好评率{{food.rating}}%</span>
                 </div>
                 <div class="price">
                   <span class="now">&yen;{{food.price}}</span><span class="old" v-show="food.oldPrice">&yen;{{food.oldPrice}}</span>
                 </div>
                 <div class="cart-control-wrapper">
                   <v-cart-ctrl :food="food" v-on:add-to-shopping-cart="addFood"></v-cart-ctrl>
                 </div>
               </div>
             </li>
           </ul>
         </li>
       </ul>
     </div>
     <v-shop-cart ref="shopCart" :select-foods="selectFoods" :delivery-price="seller.deliveryPrice" :min-price="seller.minPrice"></v-shop-cart>
     <v-food ref="food" :food="selectedFood" @add-to-shopping-cart="addFood"></v-food>
   </div>
</template>

<script>
import BScroll from 'better-scroll'
import ShoppingCart from '@/components/shopcart/ShoppingCart'
import CartCtrl from '@/components/cartcontrol/CartCtrl'
import FoodDetail from '@/components/food/Food'

const ERR_OK = 0

export default {
  props: {
    seller: {
      type: Object
    }
  },
  components: {
    'v-shop-cart': ShoppingCart,
    'v-cart-ctrl': CartCtrl,
    'v-food': FoodDetail
  },
  data () {
    return {
      goods: [],
      listHeight: [],
      scrollY: 0,
      selectedFood: {}
    }
  },
  computed: {
    currentIndex () {
      for (let i = 0; i < this.listHeight.length; i++) {
        let before = this.listHeight[i]
        let after = this.listHeight[i + 1]
        if (!after || (this.scrollY >= before && this.scrollY < after)) {
          return i
        }
      }
      return 0
    },
    selectFoods () {
      let foods = []
      this.goods.forEach((good) => {
        good.foods.forEach((food) => {
          if (food.count) {
            foods.push(food)
          }
        })
      })
      return foods
    }
  },
  created () {
    this.classMap = ['decrease', 'discount', 'special', 'invoice', 'guarantee']
    this.$http.get('/api/goods').then((response) => {
      response = response.body
      if (response.errno === ERR_OK) {
        this.goods = response.data
        // 在这个函数中调用以防内容还未加载完就执行，获取不到元素的高度导致无法滑动
        this.$nextTick(() => {
          this._initScroll()
          this._calculateHeight()
        })
      }
    })
  },
  methods: {
    selectMenu (index, event) {
      if (!event._constructed) {
        return
      }
      let foodList = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook')
      let el = foodList[index]
      this.foodScroll.scrollToElement(el, 300)
    },
    // 子组件$emit派发而来的事件
    // 监听v-on:add-to-shopping-cart="addFood"，购物车组件如果提交了'add-to-shopping-cart'事件就调用这个addFood函数
    addFood (target) {
      this._drop(target)
    },
    queryDetail (food, event) {
      if (!event._constructed) {
        return
      }
      this.selectedFood = food
      this.$refs.food.show()
    },
    _initScroll () {
      // 注意vue1.0此处是this.$els.xxxx；vue2.0此处是 this.$refs.xxx
      // 此处使用相应驼峰命名
      this.menuScroll = new BScroll(this.$refs.menuWrapper, {
        click: true
      })
      this.foodScroll = new BScroll(this.$refs.foodsWrapper, {
        click: true,
        probeType: 3
      })
      this.foodScroll.on('scroll', (pos) => {
        this.scrollY = Math.abs(Math.round(pos.y))
      })
    },
    _calculateHeight () {
      let foodList = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook')
      let height = 0
      this.listHeight.push(height)
      for (let i = 0; i < foodList.length; i++) {
        let item = foodList[i]
        height += item.clientHeight
        this.listHeight.push(height)
      }
    },
    _drop (target) {
      // 体验优化，异步执行下落动画
      this.$nextTick(() => {
        // 调用shopcart组件的drop()函数
        this.$refs['shopCart'].drop(target)
      })
    }
  }
}
</script>

<style lang="stylus" scoped>
  @import "../../common/stylus/mixin.styl"
  .goods
    position: absolute
    top: 174px
    bottom: 46px
    width: 100%
    display: flex
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
      width: 80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
        width: 56px
        line-height: 14px
        padding:0 12px
        &.current
          position: relative
          margin-top: -1px
          z-index: 10
          background: #fff
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 4px
          background-size: 12px 12px
          background-repeat: no-repeat
          &.decrease
            bg-image('decrease_3')
          &.discount
            bg-image('discount_3')
          &.guarantee
            bg-image('guarantee_3')
          &.invoice
            bg-image('invoice_3')
          &.special
            bg-image('special_3')
        .text
          display: table-cell
          width: 56px
          vertical-align: middle
          border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        background: #f2f5f7
        color: rgb(147, 153, 159)
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        border-1px(rgba(7, 17, 27, 0.1))
        &:lastChild
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            margin-bottom: 8px
            line-height: 12px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 18px
              font-size: 16px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
              color: rgb(147, 153, 159)
          .cart-control-wrapper
            position: absolute
            right: 0
            bottom: 12px
</style>
